The Northern Cheyenne people have a saying: "A nation is not defeated until the hearts of its women are on the ground. Then it's finished. No matter how brave its warriors, or how strong its weapons." Well, we are pretty sure that for much of the Native American community, the nation is near defeat.

What else can we say when one out of every three Native American women report they have been raped, or that an attempt has been made to sexually brutalise them? That is more than 2.5 times the national average. And if you think those numbers are staggering, consider who is carrying out these attacks: at least 86% of sexual assaults are reportedly being perpetrated by non-Native men, according to the US department of justice.

We don't think about such massive sexual assault rates happening in industrialised places like the US. We think about them as war crimes happening in downtrodden, developing countries. But here we have rates of sexualised violence that rival anything the Women's Media Center project Women Under Siege has documented in Sudan or the Democratic Republic of Congo, where, according to a study published in the American Journal of Public Health, 12% of women say they've been raped in their lifetime.

A culture of remarkably high impunity is also thriving. The justice department reports that it makes arrests in merely 13% of the sexual assaults reported by Native women. That comparees with 32% for white women, according to the New York Times. Native women are also not reporting crimes, because they trust that nothing will be done in the terrible knot that is the tribal lands' jurisdictional confusion (between tribal courts and the federal government), and a combination of racism, a lack of victim services, and not enough police. Whatever's going on, justice is not taking root.

"When you make that first phone call and there is one officer for the entire tribal community and he can't respond or take evidence, and then a woman experiences racism at the hospital," said Cristina Finch, the policy and advocacy director of women's human rights at Amnesty International USA,that's when a woman gives up, goes home, and tries to live the rest of her life battered and broken, struggling to survive after rape. According to Finch, racism is "a very large factor" in what is happening to Native American women.

In 2007, Amnesty published a groundbreaking report on the rape of Native women called "Maze of Injustice" . It describes the complexities that keep women suffering violence in a loop of pain. But the ache goes back much further than the last few years. "We pass on the pain through our soul and spirit," said Sarah Deer, a Native American law scholar and activist.

Colonisation brought about the original injury, but a wound has continued to be worried each time another person enacts violence against the community. Without recourse, it's hard to feel like colonisation has ever come to an end. Beyond that, rape and abuse have always stemmed from outsiders. It is well documented through oral tradition that prior to the European invasion, sexual and domestic violence was not accepted and virtually did not exist in indigenous society.

There are pieces of legislation that would alleviate some of this pain. There's the SAVE Native Women Act, which, if it makes it through Congress, would take steps to restore authority to tribes to prosecute cases of domestic violence, including against non-Native perpetrators. The Tribal Law and Order Act increases the ability for tribal courts to impose sentences for crimes committed on tribal lands to up to three years, up from one. And the Senate version of the reauthorisation of the Violence Against Women Act includes provisions that would finally allow tribal courts to prosecute non-Native people in domestic violence cases – although the House decided to write their own bill that excluded these provisions.

These are mostly encouraging steps, but we have to speed up our pace before more women are sexually violated. For too many Native women, rape is not a question of "if", it's simply a matter of "when".